The present invention relates to an apparatus and process for separating contaminants from a fluid, such as wastewater. In particular, the present invention integrates components and processes into a single unit, providing for the formation and removal of a combination of flocculent polymer and contaminants (floc) from a contaminated fluid.
Due to the continuous production of large amounts of wastewater and other contaminated fluids, there is a need to provide effective and economical purification of such fluids. Otherwise, these effluents would be introduced into the environment, potentially leading to undesirable environmental consequences. Accordingly, a variety of treatment systems have been developed to purify contaminated fluids.
Gravity separation and flotation are several of the various approaches used in fluid treatment systems. These conventional systems primarily rely on gravity clarification regions, in which heavy solids settle out of the fluid and are removed from the bottom of the treatment tank. Flotation may additionally be utilized, in which gas bubbles are employed to draw particulate matter to the surface, where it is skimmed off, typically by a scooping mechanism. Specifically, flocculent, which is a polymer used to remove contaminants from water, may be mixed with wastewater, so that it will combine with the contaminants in the fluid. This mixture of flocculent and contaminants creates floc particles, which may be aerated for flotation and then removed. Prior treatment systems often integrated these conventional components in series, sometimes with pipelines connecting the various regions. Such systems are expensive and require a large footprint.
For instance, Wang et al., U.S. Pat. No. 5,068,031, is directed to a sludge-treatment apparatus that uses flotation-gravity clarification. In particular, sludge is removed by a gravity clarification process in which heavy sludge, which settles to the bottom of the tank, is collected by a traveling scraper blade. Sludge is also removed by a flotation process in which floated scum from dissolved gas thickening is removed from the fluid surface by a sludge scoop collector.
U.S. Pat. No. 5,472,611 to von Nordenskjold et al. is directed to an apparatus and process for the purification of wastewater in several successive stages. The purification basin is divided into regions by separating walls and the water travels through each of these regions successively in the direction of current flow. In the first region the water is aerated, and then it is subjected to intermediate clarification using a sedimentation surface. The water finally travels through post-clarification aeration and sedimentation regions. Sludge is deposited and removed from the bottom of each of the sedimentation regions.
Loy, U.S. Pat. No. 5,639,371, is directed to an apparatus and process for aerating wastewater. The reactor comprises a basin that is divided into two aeration cells, which are connected in series. After the wastewater is sequentially treated in the aeration cells, it passes through an outlet to a clarifier in which solid materials settle out of the liquid.
Drewery, U.S. Pat. No. 6,106,704, is directed to a wastewater treatment system contained within a cylindrical tank, which has a top capping off its open end. Within the tank, Drewery teaches a clarifier compartment and an aeration compartment surrounding the clarifier compartment. The aeration compartment may contain two aerators. The apparatus further includes a platform on top of the tank, to which an air pump is affixed having an air line extending into the aeration compartment, and an access opening formed in the top.
Drewery, U.S. Pat. No. 6,165,359, is directed to a high strength wastewater treatment system. Specifically, this patent teaches a treatment system comprising two tanks connected by a pipeline. The first tank contains a first aerator, while the second tank contains a clarifier compartment and a second aerator. The pipe allows liquid to pass between the two tanks.
Each of the prior art references utilizes clarification regions for collecting solid materials that settle out of the liquid. Although flotation may also be utilized, the prior art systems skim off particulate matter having high water contents, typically with a scooping mechanism. A system is needed that includes a novel apparatus and process to remove contaminants from a liquid in an economical manner, without requiring large amounts of space. What is also needed is a wastewater treatment system that can integrate the components for wastewater treatment into a single unit. A system that allows for removal of floc comprised of less water content is also needed.
It is therefore an advantage of some, but not necessarily all, embodiments of the present invention to provide an apparatus and process for the treatment of contaminated fluids that integrates multiple components into a single unit for the formation and removal of floc from contaminated fluids. It is another advantage of embodiments of the present invention to provide an apparatus that alleviates the higher costs and greater footprint requirements of conventional wastewater treatment components. It is a further advantage of embodiments of the present invention to provide an apparatus that uses a rotary skimmer rather than filtration for floc separation. It is another advantage of embodiments of the present invention to provide an apparatus with a rotary skimmer and aeration design that allows for removal of floc comprised of a reduced water content than achievable with known systems. It is yet another advantage of embodiments of the present invention to provide an apparatus with first stage aerating means for improved dispersion of micro-bubbles and reduction of turbulence above a mixing zone. It is still yet another advantage of embodiments of the present invention to provide an apparatus that maximizes the density of accumulated floc in a waste tank, so that the floc may flow out of the tank.
Additional advantages of various embodiments of the invention are set forth, in part, in the description that follows and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.
Responsive to the foregoing challenges, Applicant has developed an innovative apparatus for the treatment of a contaminated fluid, comprising: an integral tank; with an inlet in the tank for introducing a mixture of flocculent polymer and a contaminated fluid into the tank; a mixer, located in a bottom region of an innermost cylinder in the tank; first stage aerating means, located within the innermost cylinder; a rotary skimmer, located above the fluid level of the innermost cylinder and a second stage aeration cylinder surrounding the innermost cylinder; second stage aerating means, located within the second stage aeration cylinder; a de-aeration baffle, located on the same plane as the rotary skimmer and extending around an outermost cylinder; fluid level control means, located between the second stage aeration cylinder and the outermost cylinder, directing fluid flow from the second stage aeration cylinder out of the tank; means for powering the mixer and the rotary skimmer; a first outlet for permitting clear fluid to exit the tank; and a second outlet for permitting waste effluent to exit the tank.
Applicant has also developed an innovative method for treating a contaminated fluid, comprising the steps of: introducing a mixture of a flocculent and the contaminated fluid into an innermost cylinder of a tank having a mixer located therein; aerating the mixture as it proceeds upward through the innermost cylinder; skimming the aerated floc formed by the flocculent and the contaminants; aerating the mixture as it proceeds downward through a second cylinder surrounding the innermost cylinder; and directing the fluid flow from the second cylinder out of the tank as a decontaminated fluid. The method may further comprise the steps of: de-aerating the skimmed floc by directing it across the surface of a de-aeration baffle into a waste tank; and accumulating the floc in the waste tank as a higher density fluid until it is released through an outlet in the tank.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference, and which constitute a part of this specification, illustrate certain embodiments of the invention and, together with the detailed description, serve to explain the principles of the present invention.